Here we have a Bourns 4:1 transformer for audio power applications that (assuming 120v input) provides a 30v center-tapped output, giving 15v - 0 - 15v.
The transformer is fully metal-enclosed and non-conductive laquered so provides good EMI shielding in a power supply used in audio equipment.
These are new, old stock. Made in the USA in approximately 1974, carrying the following markings : MS-1 P /
Measurments : - 42x42x50mm
Mounting flange = 62x16mm with 51mm between center-points of mounting holes.